Statute Miles and Nautical Miles

Date: 5/11/96 at 23:15:28
From: Anonymous
Subject: Statute Miles and Nautical Miles

Could you please tell me the difference between statute miles and 
nautical miles? Why do they use statute miles for space shuttle 
launches rather than miles per hour?

Date: 12/11/96 at 01:04:19
From: Doctor Rob
Subject: Re: Statute Miles and Nautical Miles

A mile was originally 1000 ("mille" in Latin) paces of a Roman 
soldier. In latter years it has been standardized at 5280 feet. Since 
the standardization was accomplished by law, it is more formally known 
as a statute mile. 

The nautical mile has varied in the past. It is supposed to be the 
length of one minute of arc at the equator. The actual value has been 
6080 feet, 6080.20 feet, but now it is standardized at 6076.103 feet. 
It is called a nautical mile because sailors have been using it for 
many, many years. This is due to the use of spherical trigonometry in 
navigation.

They probably use the phrase "statute miles" for space shuttle 
launches to make sure that everyone understands that these are not 
nautical miles, which is what the navy tends to use, but rather the 
more common kind that most people are familiar with from their cars' 
speedometers and odometers.

-Doctor Rob,  The Math Forum
 Check out our web site!  http://mathforum.org/dr.math/   

Date: Nov. 16, 1998
From: Michael Young

In an answer to a question sent to you in 1996 you discussed the 
difference between the statute mile and the nautical mile.  The 
value you gave for the current length of the nautical mile is not 
strictly correct.  The length you gave (6076.103 Feet) is based 
on what are now called U.S. Survey Feet.  Because of a growing 
divergence in the definitions of English Units used in the major 
English speaking countries they got together in 1958 to establish 
common standards for the inch-pound measurement system in terms 
of metric units.  The International Yard was established as 
0.9144 metres exactly.  The United States officially adopted this 
value in 1959 (See Federal Register, Vol 24, No 123, P 5348).  As 
a result of this new definition of the yard the length of a 
Nautical Mile, while still 1852 Metres, changed to 6076.11549 
International Feet.